催化裂化过程烯烃生成苯的研究

STUDY ON FORMATION OF BENZENE FROM OLEFINS IN CATALYTIC CRACKING PROCESS

以1-己烯、1-庚烯、1-辛烯、1-壬烯和1-癸烯为模型化合物,在小型固定流化床反应装置上进行催化裂化反应,研究了上述5种烯烃在不同反应温度、不同空速及不同分子筛催化剂(ZRP,Beta,REY,USY)作用下生成苯的规律,讨论分析了烯烃生成苯的反应路径以及反应条件对烯烃生成苯的影响.结果表明:C_(6)链烯烃环化生成环烯烃,然后生成苯是烯烃转化为苯的主要反应路径;常规催化裂化条件下5种烯烃在USY分子筛催化剂上生成苯的产率较低,苯产率随温度的升高而增加,随空速的增大而降低;与在REY分子筛催化剂和USY分子筛催化剂上相比,1-癸烯在Beta分子筛催化剂和ZRP分子筛催化剂上催化裂化生成苯的产率更高.为了减少催化裂化产物中苯的生成量,在允许的条件范围内,应该尽量降低反应温度,增大空速,在孔径较大并且酸密度较低的催化剂上进行反应.

Using 1-hexene,1-heptene,1-octene,1-nonene and 1-decene as model compounds,formation of benzene from olefins was studied under different reaction temperature,different space velocity with different zeolite catalysts in a small fixed fluidized bed reactor.The reaction paths of olefins to benzene and the influence of reaction conditions on olefins to benzene were discussed.The results showed that cyclization of C_(6)chain olefin to form cycloalkene and then to form benzene was the main reaction path of benzene formation.Under conventional catalytic cracking conditions,the yield of five olefins to benzene on USY catalyst is low.The yield of benzene is increased with the increase of temperature or the decrease of space velocity.The yield of benzene over Beta catalyst and ZRP catalyst is higher than that of REY catalyst and USY catalyst when 1-decene as feed.In order to reduce the amount of benzene in the catalytic cracking products,the reaction temperature should be lowered as much as possible,the space velocity should be increased,and the reaction should be carried out on a catalyst with a large pore size and a low acid density,within the allowed conditions.